1. Field of the Invention
Example embodiments of the present invention relate to a photoresist composition and a method of forming a photoresist pattern using the photoresist composition. More particularly, embodiments of the present invention relate to a photoresist composition employed in a semiconductor manufacturing process and to a method of forming a photoresist pattern using the photoresist composition.
2. Description of the Related Art
As information processing apparatuses have been developed, semiconductor devices having high integration degrees and rapid response speeds are desired. Hence, the technology of manufacturing the semiconductor devices has been developed to improve integration degrees, reliabilities and response speeds of the semiconductor devices. Accordingly, the requirements for a micro-fabrication technology such as a photolithography process have become strict.
In a semiconductor manufacturing process, a photoresist composition is used for the photolithography process. The solubility of the photoresist composition varies with respect to a developing solution and a light in an exposure process, and thus an image corresponding to a pattern exposed to the light is obtained. Photoresist is generally classified as either a positive photoresist or a negative photoresist. In the positive photoresist, a portion exposed to a light has an enhanced solubility relative to a specific developing solution. The portion exposed to the light of the positive photoresist is removed in a developing process so that a desired pattern is obtained. On the other hand, a portion exposed to a light of the negative photoresist has a reduced solubility relative to a specific developing solution. Thus, an unexposed portion of the negative photoresist is removed in the developing process to thereby form a desired pattern.
The photoresist composition generally includes a photosensitive polymer and a photoacid generator. The photoacid generator is material that generates acid (H+) in response to light in an exposure process. Acid generated from the photoacid generator reacts with a blocking group in the photosensitive polymer so that the photosensitive polymer is transformed into the state soluble to a specific solvent.
As an integration degree of a semiconductor device has been increased, a photoresist composition for forming a pattern having a high resolution has been required. A dispersion distance of acid generated from the photoacid generator is reduced, so a margin of a depth of focus decreases. Accordingly, a precise formation of minute pattern is practically difficult.
FIGS. 1 and 2 are cross sectional views illustrating a method of forming a photoresist pattern using a conventional photoresist composition.
Referring to FIG. 1, a photoresist film 20 is formed on a substrate 10 by coating a photoresist composition. A portion of the photoresist film 20 is exposed to a light using a mask (not shown). Then, a photoacid generator in the photoresist composition generates acid (H+) in an exposure process. However, sufficient light may not reach a lower portion of the photoresist film 20 so that the photoacid generator included in the lower portion of the photoresist film 20 may not generate a sufficient amount of acid.
Referring to FIG. 2, an exposed portion of the photoresist film 20 is removed from the substrate 10 in a developing process to form a photoresist pattern 22. Then, as acid is not sufficiently dispersed in the lower portion of the photoresist film 20, a pattern having a desired shape is not exactly formed. When a minute pattern is required, the above-mentioned problem becomes more serious.
Therefore, it would be desirable to have a photoresist composition that exhibits good reproducibility and a high resolution by readily dispersing acid therein.